Method of making (3-amino-1H-pyrazol-4-yl) (aryl)methanones

ABSTRACT

(3-Amino-1H-pyrazol-4-yl)(aryl)methanones which are new compounds having utility as intermediates for the preparation of aryl and heteroaryl-[7-(aryl and heteroaryl)pyrazolo[1,5-a]pyrimidin-3-yl]methanones, which are therapeutic agents.

CROSS REFERENCE TO RELATED APPLICATION

This is a divisional of application Ser. No. 06/612,811 filed May 24, 1984, now U.S. Pat. No. 4,900,836, which is in turn a continuation-in-part of application Ser. No. 06/507,317, filed on June 23, 1983, which has been abandoned.

SUMMARY OF THE INVENTION

This invention relates to new organic compounds which may be represented by the following structural formula: ##STR1## wherein R₁ is selected from the group consisting of Phenyl; phenyl substituted by one or two of the group selected from halogen, alkyl (C₁ -C₃) and alkoxy(C₁ -C₃); Phenyl tribsubstituted by methoxy phenyl substituted by one of the group consisting of dialkylamino(C₁ -C₃), methylenedioxy, alkylthio(C₁ -C₃), alkylsulfonyl(C₁ -C₃), trifluoromethyl and phenyl; pyridinyl; pyridinyl substituted by one or two of the group selected from halogen, alkyl(C₁ -C₃) and alkoxy(C₁ -C₃); thienyl; thienyl substituted by one or two of the group selected from halogen, alkyl(C₁ -C₃) and alkoxy(C₁ -C₃); furanyl; naphthalenyl; and pyrazinyl; and R₂ is selected from the group consisting of hydrogen and alkyl(C₁ -C₃).

DETAILED DESCRIPTION OF THE INVENTION

The compounds of the present invention may be readily prepared as set forth in the following reaction scheme: ##STR2##

In accordance with the above reaction scheme an appropriately substituted acetonitrile (1), where R₁ is as described above is reacted with a dimethylamide dimethylacetal (2) where R₂ is as described above. The resulting exothermic reaction produces a crystalline solid which is recovered by evaporation and dissolved in methylene chloride. This solution is passed through hydrous magnesium silicate and hexane is added to the refluxing eluate, giving the [(α-dimethylamino)methylene]-β-oxoarylpropanenitrile (3) which is then reacted with aminoguanidine nitrate (4) in the presence of 10N sodium hydroxide and a lower alkanol at reflux for several hours then evaporated to dryness and crystallized from water, ethanol or other suitable solvent, giving (5). The aminoguanidine nitrate may be replaced by other salts of aminoguanidine, such as the hydrochloride, sulfate, and the like. Alternatively, the aminoguanidine salt-sodium hydroxide combination may be replaced by an equivalent of aminoguanidine bicarbonate or thiosemicarbazide, both reagents resulting in the formation of (5).

The (3-amino-1H-pyrazol-4-yl)(aryl)methanones find utility as intermediates in the preparation of therapeutic aryl and heteroaryl[7-(aryl and heteroaryl)pyrazolo[1,5-a]pyrimidin-3-yl]methanones which are useful as anxiolytic or antiepileptic agents as well as sedative-hypnotic and skeletal muscle relaxant agents.

These aryl and heteroaryl(7-(aryl and heteroaryl)pyrazolo(1,5-a)-pyrimidin-3-yl)methanones have been found to be highly useful for drug therapy in mammals when administered in amounts ranging from about 0.1 mg to about 20.0 mg/kg of body weight per day. A preferred dosage regimen for optimum results would be from about 0.5 mg to about 10.0 mg/kg of body weight per day. Such dosage units are employed that a total of from about 10 to about 700 mg of active compound for a subject of about 70 kg of body weight are administered in a 24 hour period. This dosage regimen may be adjusted to provide the optimum therapeutic response. For example, several divided doses may be administered daily or the dose may be proportionally reduced as indicated by the exigencies of the therapeutic situation. The compounds are preferably administered orally but may be administered in any convenient manner such as by the intravenous, intramuscular, or subcutaneous routes.

The novel compounds of this invention may be readily used to prepare these aryl and heteroaryl(7-(aryl and heteroaryl)-pyrazolo(1,5-a)pyriminidin-3-yl)methanones as set forth in the following scheme: ##STR3##

The reaction of an appropriately substituted pyrazole (1) and an appropriately substituted 3-dimethylamino-1-(aryl or heteroaryl)-2-propen-1-one (2) in glacial acetic acid at reflux temperature for several hours, followed by solvent removal partitioning of the residue between saturated aqueous sodium bicarbonate and methylene chloride, passage of the organic layer through hydrous magnesium silicate and the addition of hexane to the refluxing eluate produces the desired products (3).

The substituted 3-dimethylamino-1-(aryl) or (heteroaryl)-2-propen-1-ones (2) are disclosed in one or more of U.S. Pat. Nos. 4,178,449; 4,281,000; and 4,236,005.

Pyrazolo(1,5-a)pyrimidines are prepared by condensation of 3-aminopyrazoles and substituted 3-amino-pyrazoles with 1,3-dicarbonyl compounds as described in J. Med. Chem., 18, 645 (1974); J. Med. Chem., 460 (1975); J. Med. Chem., 20, 386 (1977); Synthesis, 673 (1982) and references contained therein.

7-aryl and 7-heteroaryl(1,5-a)pyrimidines, which contain a 3-aroyl group, are synthesized by condensation of 1-aryl or 1-heteroaryl-1,3-dicarbonyl compounds with 3-amino-4-aroylpyrazoles.

The following non-limiting examples illustrate the preparation of the compounds of the present invention.

EXAMPLE 1 α-[(Dimethylamino)methylene]-β-oxo-2-furanepropanenitrile

A 50 ml portion of dimethylformamide dimethylacetal was added to 25 g of solid β-oxo-2-furanepropanenitrile. This exothermic reaction produced yellow crystals. After one hour the volatiles were removed under reduced pressure and the residue was dissolved in methylene chloride. This solution was passed through a short pad of hydrous magnesium silicate. The eluate was refluxed with the gradual addition of hexane to the point of turbidity. Cooling and filtration gave 35.2 g of the desired compound, mp 117°-125° C.

EXAMPLE 2 α-[(Dimethylamino)methylene]-β-oxo-benzenepropanenitrile

A 100 g portion of β-oxo-benzenepropanenitrile was placed in a 500 ml round-bottom flask and 110 ml of dimethylformamide dimethylacetal was added in one portion. The reaction mixture became warm and a homogeneous dark yellow solution resulted, which then solidified. After cooling to room temperature, hexane was added giving crystals which were recovered by filtration. This material (143.6 g, mp 102°-105° C.) is suitable for the subsequent reaction without further purification.

An analytical sample of this compound was obtained by dissolution in methylene chloride followed by passage through a short column of hydrous magnesium silicate, concentration of the eluate with the gradual addition of hexane until crystallization occurred, cooling and collection by filtration, mp 111°-113° C.

Following the general procedures of Examples 1 or 2, the following compounds of Examples 3-31, shown in Table I were prepared.

                                      TABLE I                                      __________________________________________________________________________     Example                                                                             Acetonitrile     Compound           MP°C.                          __________________________________________________________________________      3   β-oxo-4-fluorobenzenepropane-                                                              α-[(dimethylamino)methylene]-β-oxo-4-                                                  142-145                                    nitrile          fluorobenzenepropanenitrile                               4   β-oxo-(3-trifluoromethyl)benzene-                                                          α-[(dimethylamino)methylene]-β-oxo-3-                                                  93-96                                      propanenitrile   (trifluoromethyl)benzenepropanenitrile                    5   β-oxo-4-pyridinepropanenitrile                                                             α-[(dimethylamino)methylene]-β-oxo-4-                                                  127-128                                                     pyridinepropanenitrile                                    6   β-oxo-2-thiophenepropanenitrile                                                            α-[(dimethylamino)methylene]-β-oxo-2-                                                  136-140                                                     thiophenepropanenitrile                                   7   β-oxo-4-methylbenzenepropane-                                                              α-[(dimethylamino)methylene]-β-oxo-4-                                                  132-135                                    nitrile          methylbenzenepropanenitrile                               8   β-oxo-2-pyridinepropanenitrile                                                             α-[(dimethylamino)methylene]-β-oxo-2-                                                  88-90                                                       pyridinepropanenitrile                                    9   β-oxo-3-fluorophenylpropanenitrile                                                         α-[(dimethylamino)methylene]-β-oxo-3-                                                  63-68                                                       fluorophenylpropanenitrile                               10   β-oxo-2-chlorophenylpropanenitrile                                                         α-[(dimethylamino)methylene]-β-oxo-2-                                                  152-154                                                     chlorophenylpropanenitrile                               11   β-oxo-3-furanylpropanenitrile                                                              α-[(dimethylamino)methylene]-β-oxo-3-                                                   98-103                                                     furanylpropanenitrile                                    12   β-oxo-3,4,5-trimethoxyphenyl-                                                              α-[(dimethylamino)methylene]-β-oxo-                                                    138-140                                    propanenitrile   3,4,5-trimethoxyphenylpropanenitrile                     13   β-oxo-3,4-dimethoxyphenylpropane-                                                          α-[(dimethylamino)methylene]-β-oxo-                                                    glassy                                     nitrile          3,4-dimethoxyphenylpropanenitrile                                                                 solid                                 14   β-oxo-3-methylphenylpropanenitrile                                                         α-[(dimethylamino)methylene]-β-oxo-3-                                                  74-80                                                       methylphenylpropanenitrile                               15   β-oxo-3,5-dimethoxyphenylpropane-                                                          α-[(dimethylamino)methylene]-β-oxo-                                                    125-127                                    nitrile          3,5-dimethoxyphenylpropanenitrile                        16   β-oxo-4-chlorophenylpropanenitrile                                                         α-[(dimethylamino)methylene]-β-oxo-4-                                                  118-121                                                     chlorophenylpropanenitrile                               17   β-oxo-4-methoxyphenylpropane-                                                              α-[(dimethylamino)methylene]-β-oxo-4-                                                  128-130                                    nitrile          methoxyphenylpropanenitrile                              18   β-oxo-2-fluorophenylpropane-                                                               α-[(dimethylamino)methylene]-β-oxo-2-                                                  62-74                                      nitrile          fluorophenylpropanenitrile                               19   β-oxo-3-methoxy-                                                                           α-[(dimethylamino)methyl-                                                                   Syrup                                      phenylpropane-   ene]-β-oxo-3-methoxypneh-                                nitrile          ylpropanenitrile                                         20   β-oxo-[4-(tri-                                                                             α-[(dimethylamino)methyl-                                                                   122-123                                    fluoromethyl)-   ene]-β-oxo-[4-(trifluoro-                                phenyl]propane-  methyl)phenyl]propane-                                        nitrile          nitrile                                                  21   β-oxo-3-chloro-                                                                            α-[(dimethylamino)methyl-                                                                   Syrup                                      phenylpropane-   ene]-β-oxo-3-chlorophenyl-                               nitrile          propanenitrile                                           22   β-oxo-2,5-di-                                                                              α-[(dimethylamino)methyl-                                                                   140-143                                    chlorophenylpro- ene]-β-oxo-2,5-dichloro-                                 panenitrile      phenylpropanenitrile                                     23   β-oxo-2-methyl-                                                                            α-[(dimethylamino)methyl-                                                                   82-84                                      phenylpropane-   ene]-β-oxo-2-methylpenyl-                                nitrile          propanenitrile                                           24   β-oxo-[4-(dimeth-                                                                          α-[(dimethylamino)methyl-                                                                   208-210                                    ylamino)phenyl]- ene]-β-oxo-[4-(dimethyl-                                 propanenitrile   amino)phenyl]propane-                                                          nitrile                                                  25   β-oxo-2-methoxy-                                                                           α-[(dimethylamino)methyl-                                                                   105-115                                    phenylpropane-   ene]-β-oxo-2-methoxyphen-                                nitrile          ylpropanenitrile                                         26   β-oxo-[3,4-(meth-                                                                          α-[(dimethylamino)methyl-                                                                   118-124                                    ylenedioxy)phen- ene]-β-oxo-[3,4-(methyl-                                 yl]propanenitrile                                                                               enedioxy)phenyl]propane-                                                       nitrile                                                  27   β-oxo-4-ethoxy-                                                                            α-[(dimethylamino)methyl-                                                                   110-115                                    phenylpropane-   ene]-β-oxo-4-ethoxyphen-                                 nitrile          ylpropanenitrile                                         28   β-oxo-4-ethylphen-                                                                         α-[(dimethylamino)methyl-                                                                   48-54                                      ylpropanenitrile ene]-β-oxo-4-ethyphenyl-                                                  propanenitrile                                           29   β-oxo-2-naphtha-                                                                           α-[(dimethylamino)methyl-                                                                   115-118                                    lenylpropane-    ene]-β-oxo-2-naphthalenyl-                               nitrile          propanenitrile                                           30   β-oxo-5-methyl-2-                                                                          α-[(dimethylamino)methyl-                                                                   152-153                                    thienylpropane-  ene]-β-oxo-5-methyl-2-                                   nitrile          thienylpropanenitrile                                    31   β-oxo-2-thienyl-                                                                           α-[(dimethylamino)methyl-                                                                   118-120                                    propanenitrile   ene]-β-oxo-2-thienylpro-                                                  panenitrile                                              __________________________________________________________________________

EXAMPLE 32 α-](1-Dimethylamino)ethylidene]-β-oxo-phenylpropanenitrile

A solution of 14.5 grams of benzoylacetonitrile in 100 ml of chloroform was cooled to -10° C. and stirred as a solution of 13.3 g of N,N-dimethylacetamide dimethylacetal in 20 ml of chloroform was added dropwise during 15 minutes. The reaction temperature was not allowed to exceed -5° C. Stirring was continued at -5° to -10° C. for two hours after addition ended. The resultant reaction mixture was dissolved in 150 ml of benzene and the solution passed through a layer of hydrous magnesium silicate. Evaporation of the filtrate in air left a yellow residue which was purified by recrystallization from a mixture of benzene and low boiling petroleum ether; yield, 5.8 g, mp 105°-106° C.

EXAMPLE 33 (3-Amino-1H-pyrazol-4-yl)(2-furanyl)methanone

A reaction mixture comprising 19.0 g of α-[(dimethylamino)methylene]-β-oxo-2-furanepropanenitrile, 16.1 g of aminoguanidine nitrate, 250 ml of ethanol and 11.0 ml of 10N sodium hydroxide was refluxed for 6 hours and then evaporated to dryness. Water was added to the crude residue and the precipitated solid was collected, giving 17.0 g of the desired product, mp 153°-155° C.

EXAMPLE 34 (3-Amino-1H-pyrazol-4-yl) phenylmethanone

A reaction mixture comprising 73.36 g of α-(dimethylamino)methylene]-β-oxo-2-benzenepropanenitrile, 63.45 g of aminoguanidine nitrate, 500 ml of ethanol and 36.6 ml of 10N sodium hydroxide was refluxed for 10 hours and then cooled. The resulting precipitate was collected and washed with water, giving 17.1 g of the desired product, mp 177°-179° C.

When the aminoguanidine nitrate-10N sodium hydroxide combination was replaced by an equivalent of aminoguanidine bicarbonate, the identical product was obtained as shown by its melting point, elemental analysis and infrared and nuclear magnetic resonance absorption spectra. A similar result was obtained when an equivalent of thiosemicarbazide replaced the aminoguanidine nitrate10N sodium hydroxide combination.

Following the general procedures of Examples 33 and 34. employing the compounds of Examples 1-32 and the appropriate guanidine derivatives, the products of Examples 35-64, given in Table II, were prepared.

                                      TABLE II                                     __________________________________________________________________________          Starting Material                                                         Example                                                                             of Example                                                                              Product          MP °C.                                   __________________________________________________________________________     35    3       (3-amino-1 .sub.--H-pyrazol-4-yl)(4-                                                            172-175                                                       fluorophenyl)methanone                                           36    4       (3-amino-1 .sub.--H-pyrazol-4-yl)[3-                                                            134-136                                                       (trifluoromethyl)phenyl]methanone                                37    5       (3-amino-1 .sub.--H-pyrazol-4-yl)(4-                                                            275-277                                                       pyridinyl)methanone                                              38    6       (3-amino-1 .sub.--H-pyrazol-4-yl)(2-                                                            144-145                                                       thienyl)methanone                                                39   32       (3-amino-5-methyl-1 .sub.--H-pyrazol-4-                                                         179-180                                                       yl) phenylmethanone                                              40    7       (3-amino-1 .sub.--H-pyrazol-4-yl)(4-                                                            118-120                                                       pyridinyl)methanone                                              41    8       (3-amino-1 .sub.--H-pyrazol-4-yl)(2-                                                            177-179                                                       pyridinyl)methanone                                              42    9       (3-amino-1 .sub.--H-pyrazol-4-yl)(3-                                                            188-189                                                       fluorophenyl)methanone                                           43   10       (3-amino-1 .sub.--H-pyrazol-4-yl)(2-                                                            glassy                                                        chlorophenyl)methanone                                                                          solid                                           44   11       (3-amino-1 .sub.--H-pyrazol-4-yl)(3-                                                            211-215                                                       furanyl)methanone                                                45   12       (3-amino-1 .sub.--H-pyrazol-4-yl)(3,4,5-                                                        199-201                                                       trimethoxyphenyl)methanone                                       46   13       (3-amino-1 .sub.--H-pyrazol-4-yl)(3,4-                                                          108-109                                                       dimethoxyphenyl)methanone                                        47   14       (3-amino-1 .sub.--H-pyrazol-4-yl)(3-                                                            137-139                                                       methylphenyl)methanone                                           48   15       (3-amino-1 .sub.--H-pyrazol-4-yl)(3,5-                                                          91-92                                                         dimethoxyphenyl)methanone                                        49   16       (3-amino-1 .sub.--H-pyrazol-4-yl)(4-                                                            235-237                                                       chlorophenyl)methanone                                           50   17       (3-amino-1 .sub.--H-pyrazol-4-yl)(4-                                                            172-174                                                       Methoxyphenyl)methanone                                          51   18       (3-amino-1 .sub.--H-pyrazol-4-yl)(2-                                                            glassy                                                        fluorophenyl)methanone                                                                          solid                                           52   19       (3-amino-1 .sub.--H-pyrazol-4-yl)-                                                              96-98                                                         (3-methoxyphenyl)methanone                                       53   20       (3-amino-1 .sub.--H-pyrazol-4-yl)-                                                              172-174                                                       [4-(trifluoromethyl)phen-                                                      yl)methanone                                                     54   21       (3-amino-1 .sub.--H-pyrazol-4-yl)-                                                              229-230                                                       (3-chlorophenyl)methanone                                        55   22       (3-amino-1 .sub.--H-pyrazol-4-yl-                                                               Syrup                                                         (2,5-dichlorophenyl)metha-                                                     none                                                             56   23       (3-amino-1 .sub.--H-pyrazol-4-yl)-                                                              Glass                                                         (2-methylphenyl)methanone                                        57   24       (3-amino-1 .sub.--H-pyrazol-4-yl)-                                                              240-243                                                       [4-(dimethylamino)phenyl]-                                                     methanone                                                        58   25       (3-amino-1 .sub.--H-pyrazol-4-yl)-                                                              Glass                                                         (2-methoxyphenyl)methanone                                       59   26       (3-amino-1 .sub.--H-pyrazol-4-yl)-                                                              228-230                                                       [3,4-(methylenedioxy)phen-                                                     yl]methanone                                                     60   27       (3-amino-1 .sub.--H-pyrazol-4-yl)-                                                              155-156                                                       (4-ethoxyphenyl)methanone                                        61   28       (3-amino-1 .sub.--H-pyrazol-4-yl)-                                                              108-109                                                       (4-ethylphenyl)methanone                                         62   29       (3-amino-1  .sub.--H-pyrazol-4-yl)-                                                             215-217                                                       (2-naphthalenyl)methanone                                        63   30       (3-amino-1 .sub.--H-pyrazol-4-yl)-                                                              165-166                                                       (5-methyl-2-thienyl)metha-                                                     none                                                             64   31       (3-amino-1 .sub.--H-pyrazol-4-yl)-                                                              181-183                                                       (2-thienyl)methanone                                             __________________________________________________________________________ 

What is claimed is:
 1. A process for the preparation of a compound of the formula: ##STR4## wherein R₁ is selected from the group consisting of phenyl substituted by one or two of the group selected from halogen, alkyl(C₁ -C₃) and alkoxy(C₁ -C₃); phenyl trisubstituted by methoxy; phenyl substituted by one of the group consisting of dialkylamino(C₁ -C₃), methylenedioxy, alkylthio(C₁ -C₃), alkylsulfonyl(C₁ -C₃), amino, alkanoyl(C₁ -C₃)amino, trifluoromethyl and phenyl; pyridinyl; pyridinyl substituted by one or two of the group selected from halogen, alkyl(C₁ -C₃) and alkoxy(C₁ -C₃); thienyl; thienyl substituted by one or two of the group selected from halogen, alkyl(C₁ -C₃) and alkoxy(C₁ -C₃); furanyl; naphthalenyl; and pyrazinyl; and R₂ is selected from the group consisting of hydrogen and alkyl(C₁ -C₃);which comprises: condensing a first compound of the formula ##STR5## wherein R₁ and R₂ are as defined above; with a second compound of the formula ##STR6## or a salt or a derivative thereof.
 2. A process as defined in claim 1 which includes the step of producing said first compound by reacting a compound of the formula: ##STR7## wherein R₁ is selected from the group consisting of phenyl substituted by one or two of the group selected from halogen, alkyl(C₁ -C₃) and alkoxy(C₁ -C₃); phenyl trisubstituted by methoxy; phenyl substituted by one of the group consisting of dialkylamino(C₁ -C₃), methylenedioxy, alkylthio (C₁ -C₃), alkylsulfonyl (C₁ -C₃), amino, alkanoyl(C₁ -C₃)amino, trifluoromethyl and phenyl; pyridinyl; pyridinyl substituted by one or two of the group selected from halogen, alkyl(C₁ -C₃) and alkoxy(C₁ -C₃); thienyl; thienyl substituted by one or two of the group selected from halogen, alkyl(C₁ -C₃) and alkoxy(C₁ -C₃); furanyl; naphthalenyl; and pyrazinyl; with a compound of the formula: ##STR8## wherein R₂ is selected from the group consisting of hydrogen and alkyl(C₁ -C₃).
 3. A process as defined in claim 1 wherein (3-amino-1H-pyrazol-4-yl)(2-furanyl)methanone is produced.
 4. A process as defined in claim 1 wherein (3-amino-1H-pyrazol-4-yl)(4-pyridinyl)methanone is produced.
 5. A process as defined in claim 1 wherein (3-amino-1H-pyrazol-4-yl)(2-thienyl)methanone is produced.
 6. A process as defined in claim 1 wherein (3-amino-1H-pyrazol-4-yl)(2-pyridinyl)methanone is produced.
 7. A process as defined in claim 1 wherein (3-amino-1H-pyrazol-4-yl)(3-furanyl)methanone is produced. 